Is the contactor engaging? Make sure it is getting 24v. If not, check the low pressure safety, outside thermostat (if you have one) and the defrost board. Follow the low voltage from the thermostat to all these controls, up to the contactor. Check the thermostat too. If you need a walk through I can help, if you have a volt/ohm meter.

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Multiple problems. Eliminate thermostat first. Remove face from wall and turn on breaker. If fan still runs you have a bad board or bad relay. If fan outside is running compressor should be too. These operate on same contactor. Verify you are getting 24 volts to coil side of contactor. If odf stops working and contactor remains pulled in you have a bad motor. If odf motor stops working the compressor will shut off due to overheating.

Blower? Internal house air blower I assume. - Blower relay contacts pitted and stick in on position. BAD Control BOARD, fault or adjustment program keeping relay energized. Bad emperature sensor not telling Board unit has use up cold air. loose wiring to sensors and board connections

Hi, if the unit had a leak in it, was the leak located and repaired? Did he check the pressures in the unit now? If it switches to the aux mode ( Heat Strips ) is normally caused when your primary unit, compressor and freon are low on charge. I would have that checked. Sincerely,Shastalaker7A/C, & Heating Contractor

Hi, the schematic would be in the indoor unit, but I am assuming its gone since you are looking for the ladder schematic for the heat strips and fan control. You might try this number for a schematic, 1-888-441-6942, Route A/C and they may be able to help you on this diagram. The number you are showing does not look like any model number at all. For both the indoor and outdoor units on the Intertherm, would look something like this...., P3RA-024k for the model number, and the serial number would be right below it. Both should be very easy for you to locate. It is very hard to find schematics for units once they are gone, as some tech's like to take them off units to go home and try and study them!!, unreal! Makes it hard to troubleshoot when you need it. Try to find numbers like I have noted, and call this number as they will answer questions you may have concerning yours. I hope the best for you and would like for you to rate me, as I know you will be kind. Please keep me posted on this as maybe I can help you solve this fan relay problem you have? Sincerely,Shastalaker7A/C, Heating, & Refrigeration Contractor

Make sure fan relay is wired correctly (G) wire. Ensure the fan on therm is not on, it should be on Auto or off.

If your furnace is short cycling because it has to keep heating your home, the delay in the control board may be staying on to compensate for the exchangers getting hot. If it heats normally, then put your attention to your thermostat.

Set the heating system on aux heat only. Fan should not be on, if it does stay on after a heating cycle, see if the furnace is heating normally, and reaching temp as desired before the heat comes off. Then check the therm wiring, pull the face of the therm, disconnect green wire (fan) and try the heating again.

It sounds like the unit is going into a defrost cycle, which is normal for heat pumps and means all is working ok when it gets around 35 or colder they start to do this more often when the red light goes back off , the outdoor fan should come back on. You may also notice steam (may look like smoke) coming from outdoor unit. Is that what happens??